Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $188.61   3.798%   $195.7734   $195.77   $195.75   $195.80  
  Purchase #2 $237.84   11.797%   $265.898   $265.90   $265.90   $265.90  
  Purchase #3 $241.59   13.455%   $274.0959   $274.10   $274.10   $274.10  
  Purchase #4 $161.42   9.535%   $176.8114   $176.81   $176.80   $176.80  
  Purchase #5 $87.77   6.440%   $93.4224   $93.42   $93.40   $93.40  
  Purchase #6 $191.93   11.198%   $213.4223   $213.42   $213.40   $213.40  
  Purchase #7 $235.28   6.431%   $250.4109   $250.41   $250.40   $250.40  
  7 purchase totals = $1,344.44       $1,469.8343   $1,469.83   $1,469.75   $1,469.80